I. ˈ ̷ ̷ˌ ̷ ̷ noun
( -s )
Etymology: back up
1. : backing
supported by military strength in being and strength in potential timely backup — M.B.Ridgway
a stiff backup to the sheet so that it would not bend
2. : an accumulation especially as a result of the stoppage of a flow
a backup of sewage
a backup of cars before the intersection
: reserve
a backup of material for emergency use
3. : a backward movement : a retreat from a position
asked Congress for a backup on its policy and a repeal of the law
4. : a ball that curves or fades to the right in bowling
5. : a masonry backing to a wall
6. : the presswork on the second side of a printed sheet
II. noun
1. : one that serves as a substitute or alternative
the second spacecraft would be a backup in case of failure
2. : accompaniment 1
the tunes included banjo and guitar backup
3. : a copy of computer data (as a file, a program, or all the files of a hard disk) ; also : the act or an instance of making a backup
III. ¦ ̷ ̷ ˌ ̷ ̷ adjective
1. : serving as a backup
a backup guidance system
2. : serving as an accompaniment
he records as a soloist with backup musicians — Ellen Sander